Initially Core V30 removed filters on OP_RETURN sizes that protects against spam. However, on the consensus level, OP_RETURN don't have a size limit so miners were already spamming data on chain anyway. Core V30 making this easier definitely sucks, especially considering the way they forced it despite community backslash, but the fact remains that the attack vector was there all along. BIP110 is aiming at fixing that by making consensus changes, however it is poorly engineered and will also prevent several some of the most promising ways to scale bitcoin. Moreover, the way they're trying to force their bad solution through is hostile in itself and suggest that it is more about a personal vendetta than about bitcoin future. 🤔